1. Field of the Invention
This invention relates to scanning microscopes requiring miniature optical heads, in particular but not limited to laser scanning microscopes with miniature heads which can be utilized as an endoscope.
2. Description of the Related Art
In order to construct a scanning microscope which has an optical head small enough to be inserted in the body to act as an endoscope, whereby internal organs of the body may be inspected at a microscopic level, the optical head of the scanning microscope must be able to be located physically independently of the bulky light source and photo-multiplier tube, and also must be miniaturized.
U.S. Pat. Nos. 5,120,953 and 5,161,053 (“Harris” and “Dabbs” respectively) describe how a confocal microscope may be constructed using optical fibers to make the optical head geometrically independent from the light source and/or detector. Harris and Dabbs further disclose how a single fiber may be used to construct a microscope where the exit end of the fiber acts as both the source pinhole and return pinhole in a confocal microscope.
Harris also describes embodiments where the fiber tip is vibrated to produce a miniature optical head suitable for an endoscope application. One practical problem with such a design is that the scanning accuracy of the system is limited by the kinetic energy transfer to (and losses from) the vibrating components of the scanning mechanism.
An alternative endoscope design remotely locates the scanning apparatus, and transmits the light down a standard endoscopic optical fiber bundle. This can be implemented by positioning the imaging end of the fiber bundle at the microscope stage of a laser scanning confocal microscope, or by using special optical arrangements as described in U.S. Pat. No. 5,323,009. This results at the specimen end of the fiber bundle in a corresponding scanning of the illuminating spot. A disadvantage with such systems is that the optical resolution is limited by the discrete nature of the fiber cores in the endoscopic bundle.